Pore Engineering and Competitive Kinetics for Selective Dye Adsorption on γ‑Fe₂O₃ Nanoparticles

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Adsorption is key for dye separation, but separating similar dyes remains challenging.
• Porous nanomaterials offer potential for selective dye adsorption.
• Understanding dye-molecule interactions with adsorbent pore structure is vital.

Purpose of the Study:

• Investigate competitive adsorption of methylene blue (MB) and safranin O (SO) on γ-Fe2O3 nanoparticles.
• Examine the influence of tunable pore size on dye selectivity.
• Determine factors governing selective dye adsorption.

Main Methods:

• Synthesized porous γ-Fe2O3 nanoparticles.
• Modified pore size using citrate buffer leaching and pretreatment.
• Performed competitive adsorption experiments with MB and SO.
• Analyzed adsorption kinetics and thermodynamics.

Main Results:

• Pretreated nanoparticles with enhanced pore sizes showed increased adsorption capacity for both MB and SO.
• Selectivity for MB increased as pore size decreased (10% at 3.4 nm, 22% at 2.2 nm).
• MB exhibited higher adsorption kinetics despite thermodynamic preference for SO, attributed to mass transfer in accommodating pores.

Conclusions:

• Adsorbent pore size is a critical factor for selective dye adsorption.
• Optimizing pore size, alongside adsorption thermodynamics and kinetics, enhances dye selectivity.
• Tailoring γ-Fe2O3 nanoparticle pore structure is a promising strategy for efficient dye separation.